This application claims the priority of European patent application 99114647.3, filed Jul. 27, 1999, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a punching and stamping machine having a machine frame, a die, die plate, and a workpiece holder.
Punching and stamping machines are known in many different constructions. The principal tool of these machines is a die which is caused to strike against or strike through the workpiece at high pressure, which workpiece, as a rule, rests on a die plate or against a die plate. The first case involves stamping, the second case involves punching. In the case of a punching, the material in the shape of the die or the die plate is removed from the workpiece; in the case of a stamping, a plastic deformation of the respective material is achieved in the workpiece. There are also mixed forms, in the case of which, for example, bow-type areas are to be formed from an originally closed workpiece surface. In these cases, the concerned area is partially punched out of the workpiece by means of the die but remains connected with the workpiece by way of bridges.
The workpieces worked by means of such machines are predominantly metals, which requires that the forces to be applied by the die must be very large in order to achieve a plastic deformation or separation of the material.
The forces are conventionally transmitted to the die either mechanically by means of an eccentric shaft or hydraulically. As a rule, the conventional mechanical machines have very large dimensions, because the force must be built up and transmitted directly at the site of the die, and are suitable for the machining of large piece parts. Since the pressure buildup takes place separately from the die, the hydraulic machines may also have a smaller construction and are also suitable for machining smaller components.
Specifically when machining cylindrical hollow bodies, problems occur, on the one hand, because of the partly very small dimensions of the workpieces and, on the other hand, during the positioning of the die and the die plate, particularly when the cylindrical workpiece is to be machined along its circumference at certain points frequently situated at regular distances.
Because of the large stroke movements of the die, conventional mechanical machines for machining the workpieces from the inside to the outside cannot be used for small workpieces because these movements cannot be carried out in the interior of the workpiece. The same problem occurs in the case of machines for the machining of workpieces from the outside to the inside because there the die plate cannot carry out the required stroke movement in the interior of the workpiece.
Normally, hydraulic machines are therefore used for this field of application. Although, in this case, the short-stroke die and the die plate are guided on a common guide, they are not forcibly coupled with one another. Among other things, this limits the maximal working speed, which has an effect particularly in the case of workpieces where a large number of punching or stamping operations are to be carried out along their circumference.
It is an object of the present invention to provide a punching and stamping machine which permits a reliable, fast punching or stamping, particularly of hollow-cylindrical workpieces.
According to the invention, this object is achieved by providing a punching and stamping machine having a machine frame, a die, a die plate and a workpiece holder for receiving a workpiece,
wherein the die plate is held in a displaceably guided die plate frame which is displaceably guided by way of a plate cam with respect to the workpiece holder in the machine frame,
wherein the die is connected with an eccentric shaft which is rotatably disposed in the die plate frame, and
wherein the eccentric shaft and the plate cam are directly coupled with one another and are connected with a drive shaft.
This object is also achieved by using this machine to make parts.
By means of the forced coupling of the movement of the die plate and of the die as well as the superimpositions of these two movements with respect to the workpiece to be machined or its holding device, in the case of only a very slight relative movement between the die and the workpiece, a reliable and sufficient punching and stamping effect is achieved onto the workpiece. This allows the die to act also from the interior side of hollow-cylindrical workpieces with relatively small internal radii toward the outside. However, in this case, the die can nevertheless be dimensioned to be sufficiently large for permitting the force transmission without any risk of breakage or deformation also at high machining speeds. The same applies when the workpieces are machined from the outside, in the case of which the die plate is arranged on the interior side of the workpiece and advantageously can also be dimensioned to be sufficiently large. In addition, as a result of the forced coupling of the die and the die plate, a high precision of the stamping or punching is achieved.
The plate cam is preferably coupled with the eccentric shaft to be adjustable at the relative torsion angle in order to adapt the movements with respect to the workpiece holder and the workpiece corresponding to the requirements. The shape of the plate cam will also be adapted corresponding to the requirements. Thus, a machine according to the invention, for example, may have a set of different plate cams which are used depending on the demand or application.
When preferably the drive of the eccentric shaft takes place by way of a controlled servo shaft, the precision and adjustability can be further increased, and, in synchronization with the controlling of a workpiece holder which is preferably further developed rotatably by way of a servo motor, stamping and punching of hollow-cylindrical workpieces can take place along their circumference at high machining speeds and with high precision.
Even if preferably hollow-cylindrical workpieces can advantageously be machined by means of such a machine, its use is not limited solely to that purpose.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.